The far-field pattern of an antenna is its response to uniform plane-wave illumination at various incident angles. Three distinct approaches exist for measuring an antenna's pattern. The oldest approach is to illuminate the antenna with a distant source. However, a high gain antenna requires an excessive separation from the source. A second approach, referred to as near-field sampling, measures the field amplitude and phase distribution within the near field of the antenna and mathematically transforms these measurements to obtain a far field pattern. This approach requires accurate positioning of a probe and limits the angular range of the calculated patterns. The third approach, referred to as a compact range, uses the collimated near-field close to the aperture of a large offset reflector or lens as a test field. This approach requires a larger compact range antenna than that being tested and design attention to scattering components that can degrade measurement accuracy.
It would be helpful to be able to provide an antenna range design that produces test fields having sufficient uniformity for antenna testing, using the near field of a conventional reflector antenna. It would be helpful if such an antenna range design also limits multipath degradation, as well as provides high measurement sensitivity.